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| United States Patent |
5,068,490
|
|
Eaton
|
November 26, 1991
|
BF3-tertiary etherate complexes for isobutylene polymerization
Abstract
Disclosed herein are boron trifluoride etherate complexes in which the
ether of the complex has at least one tertiary carbon bonded to an ether
oxygen. The etherates are useful for polymerizing a one-olefin or mixtures
thereof, preferably comprising isobutylene, whereby the resulting polymer
contains a high percentage (80-100%) vinylidene character.
| Inventors:
|
Eaton; Bruce E. (Naperville, IL)
|
| Assignee:
|
Amoco Corporation (Chicago, IL)
|
| Appl. No.:
|
534696 |
| Filed:
|
June 6, 1990 |
| Current U.S. Class: |
585/525; 423/293; 502/203 |
| Intern'l Class: |
C07C 002/08 |
| Field of Search: |
585/525
423/293
502/203
|
References Cited
U.S. Patent Documents
| 2384916 | Sep., 1945 | Holmes | 260/93.
|
| 2559062 | Jul., 1951 | Dornte | 260/93.
|
| 2559984 | Jul., 1951 | Montgomery et al. | 260/683.
|
| 2588425 | Mar., 1952 | Stevens et al. | 260/683.
|
| 2777890 | Jan., 1957 | Ikeda | 260/680.
|
| 2780664 | Feb., 1957 | Serniuk | 260/683.
|
| 3006906 | Oct., 1961 | Geiser | 260/94.
|
| 3962375 | Jun., 1976 | Throckmorton | 526/335.
|
| 4098983 | Jul., 1978 | Osborn et al. | 585/525.
|
| 4152499 | May., 1979 | Boerzel et al. | 526/52.
|
| 4849572 | Jul., 1989 | Chen et al. | 585/525.
|
| Foreign Patent Documents |
| 576759 | May., 1959 | CA.
| |
| 804070 | Nov., 1958 | GB.
| |
Primary Examiner: Pal; Asok
Attorney, Agent or Firm: Riley; Reed F., Magidson; William H., Medhurst; Ralph C.
Parent Case Text
This is a continuation of application Ser. No. 396,380, filed Aug. 18,
1989, which is a continuation of U.S. Ser. No. 162,046, filed Feb. 29,
1988, now both abandoned.
Claims
I claim:
1. A process to form a product which is essentially polyisobutylene
containing at least about 80 percent vinylidine, which process comprises
polymerizing isobutylene or a mixed C.sub.4 hydrocarbon feedstock
containing at least about 5 weight % isobutylene and up to 20 parts per
million water with a boron trifluoride etherate complex wherein the ether
of said complex has at least one tertiary carbon bonded to the ether
oxygen.
2. The process of claim 1 wherein the boron trifluoride etherate has the
general formula:
##STR3##
wherein R.sub.1 is a C.sub.1 to C.sub.20 hydrocarbyl or halo-substituted
hydrocarbyl and R.sub.2, R.sub.3, and R.sub.4, being the same or
different, are selected from the group consisting of (a) --CH.sub.2 R',
where R' is H, halogen, or a C.sub.1 to C.sub.20 hydrocarbyl (b)
--CH.dbd.R", and (c) --C.tbd.R"', wherein R" and R"' are the same or
different and R" and R"' are selected from a C.sub.1 to C.sub.20
hydrocarbyl or halo-substituted hydrocarbyl.
3. The process of claim 2 wherein R.sub.2, R.sub.3 and R.sub.4 are methyl.
4. The process of claim 3 wherein R.sub.1 is selected from the group
consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl.
5. The process of claim 4 wherein R.sub.1 is methyl.
6. The process of claim 5 wherein the etherate is the reaction product of
the ether and boron trifluoride reacted in a mole ratio of at least about
1:1.
7. The process of claim 4 wherein R.sub.1 is butyl.
8. The process of claim 7 wherein the etherate is the reaction product of
the ether and boron trifluoride reacted in a mole ratio of at least about
1:1.
9. The process of claim 4 wherein R.sub.1 is isopropyl.
10. The process of claim 9 wherein the etherate is the reaction product of
the ether and boron trifluoride reacted in a mole ratio of at least about
1:1.
Description
FIELD OF THE INVENTION
The present invention relates generally to BF.sub.3 -etherate complexes
useful for polymerization of 1-olefin containing feedstocks. More
particularly the invention is directed to BF.sub.3 -etherates in which the
ether of the BF.sub.3 -etherate has at least one tertiary carbon bonded to
an ether oxygen, and to a process for polymerizing feedstocks comprising
isobutylene wherein the BF.sub.3 -tertiary etherate is the catalyst. The
BF.sub.3 -tertiary etherates of the present invention and the
polymerization process employing them are suitable for manufacturing
polybutene having a very high percentage (80 to 100%) of vinylidene
olefin.
DISCUSSION OF THE PRIOR ART
Generally speaking, polymerization of 1-olefin containing feedstocks using
catalysts such as aluminum chloride and boron trifluoride is disclosed
extensively in the patent and technical literature. It is well known that
the termination step in isobutylene polymerization results in a "terminal"
double bond which imparts desired reactivity to the polymer for subsequent
reactions, such as epoxidization or reaction with maleic anhydride.
However, a problem exists in that the termination step can place the
terminal double bond in a highly reactive external 1,1-disubstituted
position (hereafter "vinylidene"), or in a much less reactive internal
tri-substituted or tetrasubstituted position. These three possible
terminal double bond positions are shown below.
##STR1##
Referring to this problem, Samson U.S. Pat. No. 4,605,808 states that the
product obtained upon conventional polymerization of isobutylene is
generally a mixture of polymers having a high proportion of internal
versus external (vinylidene) unsaturation due to "in situ" isomerization
of the more highly reactive vinylidene double bond to the less reactive
internal positions. The diminished reactivity of the hindered internal
tri-substituted or tetra-substituted double bond is most notably observed
in the manufacture of the valuable intermediate polyisobutenyl succinic
anhydride ("PIBSA") which is obtained by reaction of maleic anhydride with
polybutene. PIBSA is a very important intermediate in the manufacture of
fuel and lubricant additives. The lowered reactivity of polybutene due to
the presence of substantial internal olefinicity reduces the yield of
PIBSA when the polymer is reacted with maleic anhydride and thus dictates
higher usage of polybutene than would otherwise suffice if the polybutene
consisted mainly of vinylidene olefin.
Given the above problem, it has long been an object of research in the area
of polybutene manufacture to improve the reactivity of polybutene,
particularly its reactivity toward maleic anhydride, by identifying
catalysts or catalyst systems capable of polymerizing isobutylene such
that the resulting polybutene has the highest possible percentage of
vinylidene double bonds.
A number of patents have sought to address this very problem. Nolan U.S.
Pat. No. 3,166,546 discloses a vapor phase process for isobutylene
polymerization which requires using a mixture of gaseous boron trifluoride
and sulfur dioxide under specified conditions. The patent states that
sulfur dioxide directs the polymerization reaction such that substantially
all of the polybutene has vinylidene unsaturation. In column 1 of the
patent, it is stated that the boron trifluoride catalyst requires a small
amount of water, alcohol, carboxylic acid, mineral acid or ether to
initiate the catalyst. However, there is no suggestion for the use of
BF.sub.3 -tertiary etherate complexes. Moreover, the sulfur dioxide
process does not appear to be commercially viable.
In later work using BF.sub.3 catalyst, Boerzel et al. U.S. Pat. No.
4,152,499 disclosed that BF.sub.3 mainly favors the formation of polymer
having the reactive double bond in the vinylidene position if a short
polymerization time (3 to 5 minutes) is strictly maintained.
Most recently, Samson U.S. Pat. No. 4,605,808 discloses isobutylene
polymerization using a preformed boron trifluoride/alcohol complex and
contact times in the range of 8 to 70 minutes, as a means of obtaining a
high percentage (at least 70 percent) of vinylidene content in the
resulting polybutene polymer.
While the patents cited above dealing with BF.sub.3 catalysis are
indicative of progress toward the achievement of a highly reactive (high
vinylidene) polybutene, a number of problems remain to be solved. First,
the teachings of these patents place strict restraints on the contact time
for the catalysts. For example, in the case of the above cited Boerzel
Patent, a contact time of 1 to 10 minutes is claimed but 3 to 5 minutes is
the preferred range. If the brief contact times are not maintained, the
desired high levels of vinylidene unsaturation cannot be achieved given
the tendency of the vinylidene double bonds in the polymer to isomerize in
the presence of the catalyst to the less reactive internal type double
bond.
To some extent, this problem may have been alleviated in the Samson '808
patent teaching use of a preformed boron trifluoride/alcohol complex with
contact times of 8 to 70 minutes to obtain polymer having at least 70%
vinylidene content. Nevertheless, it is desired to increase even further
the percentage of vinylidene content obtainable in the polymer, while at
the same time eliminating or minimizing the dependency of such outcome
upon rigorously maintained contact times.
Inasmuch as the present invention relates generally to isobutylene
polymerization in the presence of boron trifluoride etherate complexes, a
number of additional literature references and patents, in addition to
those already discussed above, are believed to be of general relevance
although they fail to address the problem sought to be overcome by the
present invention and can be readily distinguished. For example, Dornte
U.S. Pat. No. 2,559,062 discloses isobutylene polymerization using boron
trifluoride complexed with di-n-butyl ether, halogen-substituted dialkyl
ethers, aryl-alkyl mixed ethers, nitroaryl ethers, cyclic ethers and
unsaturated ethers. The patent notes that the types of ethers used for
complexation with BF.sub.3 may not be indiscriminately selected, and makes
no mention of tertiary etherates in which a tertiary carbon is bonded to
the ether oxygen.
Stevens et al. U.S. Pat. Nos. 2,588,425 and 2,591,384 disclose preparation
of an isobutylene polymer consisting almost exclusively of
tetraisobutylene or triisobutylene. The tetramer or trimer is prepared
from isobutylene at 0.degree. C. to 55.degree. C. in the presence of a
boron trifluoride ether complex. The ether compounds disclosed by Stevens
do not include tertiary ethers.
Montgomery et al. U.S. Pat. No. 2,559,984 teach the use of aluminum
chloride or boron fluoride catalysts complexed with organic compounds, but
the patent mentions ethers only in the context of aluminum chloride
catalysts.
Ikida U.S. Pat. No. 2,777,890 discloses the use of a boron trifluoride
diethylether complex as a catalyst for polymerization of butadiene-1,3.
Throckmorton U.S. Pat. No. 3,962,375 discloses boron trifluoride complexed
with ethers of the formula ROR' where R and R' represent alkyl,
cycloalkyl, aryl, alkyaryl, arylalkyl radicals containing from 1 to about
30 carbons.
Serniuk U.S. Pat. No. 2,780,664 discloses preparation of a drying oil by
contacting a mixture of 75 parts by weight of butadiene and 25 parts by
weight of isobutylene in the presence of boron trifluoride ethylether
complex.
Geiser U.S. Pat. No. 3,006,906 discloses copolymerization of isobutylene
with a tetra-substituted alkylene diamine in the presence of a boron
trifluoride ethylether complex.
Holmes U.S. Pat. No. 2,384,916 discloses a method of producing high
molecular weight iso-olefin polymers using boron trifluoride catalysts
promoted with ethylether, normal propylether, isopropylether, normal
butylether, methyl normal butylether and isomaylether. The use of boron
trifluoride:tertiary ether complexes to obtain polybutene having high
levels of vinylidene unsaturation is no where disclosed or suggested in
this patent.
Finally, it should be noted that early work by Evans et al. determined the
necessity in BF.sub.3 catalysis of a complexing agent able to donate a
proton. Evans discovered that no polymerization will occur when pure
diisobutylene is exposed to BF.sub.3 unless a trace amount of moisture is
present. This finding has generally led to the acceptance of a cationic
mechanism, and therefore the requirement of a proton source, for both
BF.sub.3 and AlCl.sub.3 catalysis. The early work of Evans in conjunction
with his associates, Meadows and Polanyi, is described in Nature (1947)
160, page 869; J. Chem. Soc. (1947) 252; and Nature (1946) 158, page 94.
To date, the cationic mechanism ascribed to BF.sub.3 and AlCl.sub.3
catalysis requiring proton donation to initiate polymerization is widely
accepted.
To the best of my knowledge the patents and literature references discussed
above with respect to the use of BF.sub.3 -etherate complexes are not
addressed to the attainment of high vinylidene content in polybutene and
do not teach tertiary etherates capable of achieving that result. On the
contrary the BF.sub.3 ether complexes taught in these early patents are
inactive unless they are activated with a proton source. Under the
accepted cationic mechanism for such polymerization the actual BF.sub.3
catalyst in the presence of such a proton source acts as a Lewis acid
having a strong tendency to isomerize the vinylidene double bonds to the
less reactive internal double bonds and to cause skeletal rearrangements
and branching of the polybutene formed during the polymerization reaction.
The latter is a disadvantage in that a highly linear polymer is generally
preferred in lubricant additive manufacture.
In view of the foregoing discussion of the prior art, an object of the
present invention is generally to provide an improved BF.sub.3 catalyst
system useful in the preparation of polybutene having a high percentage of
vinylidene unsaturation. Other objects will be apparent hereinafter to
those skilled in the art.
SUMMARY OF THE INVENTION
I have now discovered an improved boron trifluoride catalyst system for use
in the polymerization of 1-olefin containing feedstocks. The catalyst
system comprises a BF.sub.3 -etherate complex in which the ether has at
least one tertiary carbon bonded to an ether oxygen. The tertiary ether
can have the general formula:
##STR2##
where R.sub.1 is C.sub.1 to C.sub.20 hydrocarbyl or halo-substituted
hydrocarbyl and R.sub.2 R.sub.3 and R.sub.4, the same or different, are
selected from the group consisting of (1)--CH.sub.2 R' where R' is H,
halogen, or C.sub.1 to C.sub.20 hydrocarbyl or halo substituted
hydrocarbyl; (2)--CH.dbd.R" where R" is C.sub.1 to C.sub.20 hydrocarbyl or
halo substituted hydrocarbyl; and (3)--C.tbd.R"' where R"' is C.sub.1 to
C.sub.20 hydrocarbyl or halo substituted hydrocarbyl. Preferred tertiary
ethers for use in preparation of the BF.sub.3 -etherate complexes of the
present invention are those in which R.sub.2, R.sub.3 and R.sub.4 in the
above formula are methyl, and R.sub.1 is C.sub.1 to C.sub.10 hydrocarbyl.
Particularly preferred are the alkyl tert-butyl ethers, e.g., methyl
t-butyl ether, n-butyl t-butyl ether, isopropyl t-butyl ether,
di-tert-butyl ether, ethyl tert-butyl ether, pentyl tert-butyl-ether,
1,1'-dimethylbutyl methylether, etc.
As a method, the present invention is directed to a process for
polymerizing a feedstock comprising 1-olefin which process comprises the
step of contacting the feedstock with a BF.sub.3 -tertiary etherate as
described above at -100.degree. to +50.degree. C. The process is suitable
for polymerizing isobutylene to obtain commercial grade polybutene having
high percentages of vinylidene olefinicity (i.e., 80 to 100%).
A principle advantage of the BF.sub.3 -tertiary etherate complexes of the
present invention is their ability to produce polybutene polymer having
higher percentages of vinylidene unsaturation (80 to 100%) than obtained
using the BF.sub.3 -catalysts of the prior art (i.e., Boerzel U.S. Pat.
No. 4,152,499 and Samson U.S. Pat. No. 4,605,808) which, by comparison,
are taught to be capable of producing vinylidene contents in the range of
only about 60 to 90%.
The etherates of the present invention also compare favorably to the
BF.sub.3 -alcoholate complexes of Samson in their ability to produce
higher molecular weight polymer at a given temperature.
Still a further advantage is that longer residence times are acceptable in
the BF.sub.3 -etherate catalyzed polymerization of the present invention.
Residence times of 10 minutes to 3 hours (or greater) can be used
depending upon temperature, catalyst concentration and desired molecular
weight.
Further advantages include the fact that the BF.sub.3 -etherates of the
present invention are more active than BF.sub.3 -alcohol complexes and
show greater selectivity for isobutylene than conventional AlCl.sub.3
catalyst. This latter advantage reduces the stripping required for the raw
polybutene product.
Finally, in comparison to aluminum chloride catalyzed polymerization, the
polybutene product resulting from the BF.sub.3 -tertiary etherates of the
present invention is more linear (less branching and skeletal
rearrangements) and is consistently colorless.
Surprisingly, unlike the prior art BF.sub.3 catalyst systems which require
a protic source (i.e., water, alcohol, mineral acid, etc.) to initiate
polymerization, the BF.sub.3 -tertiary etherate complexes of the present
invention do not require protic initiation. In fact, they are found to
perform optimally in terms of high vinylidene content, using feeds that
are essentially completely free of water or other protic species capable
of complexing with the BF.sub.3 by displacement of the tertiary ether. As
the presence of water or other proton donating species in the feed or
reaction zone increases, even slightly, the ability of the BF.sub.3
-tertiary etherates to produce high vinylidene falls off dramatically.
Therefore the preferred feedstock for use in the present invention should
be as anhydrous as possible, preferably containing no greater than about 1
to about 10 ppm water. However feeds having 10 to 20 ppm H.sub.2 O can be
used without seriously impairing the advantages of the present invention.
At levels greater than about 20 ppm H.sub.2 O, the BF.sub.3 etherates of
the present invention may perform worse than the prior art BF.sub.3
catalysts measured in terms of the ability to produce high vinylidene
content in the polymer product.
Without any intention to be bound to a particular theory, it is believed
that the advantages noted above, namely higher vinylidene content, longer
residence times, higher molecular weight polymer, more linear polymer,
etc., result from the fact that the BF.sub.3 tertiary etherates of the
present invention do not require protic initiation for polymerization to
take place. Protic initiation, characteristic of a cationic mechanism for
isobutylene polymerization results in a reaction environment which is
highly acidic due to the proton donation by the active catalyst species,
such active species being a complex of the protonic entity (for example
water) and the BF.sub.3. The acidic reaction environment characteristic of
proton initiated polymerization is believed the principle cause underlying
isomerization of terminal vinylidene unsaturation to the less desired and
less reactive internal unsaturation. Acidity at the onset of
polymerization resulting from proton donation of the catalyst species also
causes skeletal rearrangements and fragmentation of the forming polybutene
polymer. By comparison, in view of the evidence that the BF.sub.3 tertiary
etherate complexes of the present invention are capable of operating in an
essentially completely anhydrous environment requiring no protic
initiation, polymerization in accordance with the present invention is
initiated in a substantially nonacidic environment which reduces acid
catalyzed isomerization of vinylidene double bonds to di-, tri- and
tetra-substituted internal double bonds. Also, fragmentation and skeletal
rearrangements are minimized. As distinguished from a cationic mechanism,
it is believed that polymerization in the present invention proceeds via a
covalent mechanism.
A critical feature of the present invention which dictates the ability of
the BF.sub.3 -etherates disclosed herein to produce high vinylidene
polymer and to operate without necessity of protic initiation, is that the
ether in the BF.sub.3 -etherate complexes must have at least one tertiary
carbon bonded to the ether oxygen. BF.sub.3 -etherates which do not
fulfill this requirement are outside the scope of the present invention
and will not polymerize isobutylene in such a manner as to produce the
very high levels of vinylidene possible in the present invention.
DETAILED DESCRIPTION
The BF.sub.3 -tertiary etherates of the present invention can be prepared
by reacting gaseous BF.sub.3 with a tertiary ether under carefully
controlled conditions of temperature and rate of reaction whereby the
exothermicity of the BF.sub.3 -etherate complex formation is prevented
from causing the decomposition of the complex. In the case of the BF.sub.3
-methyl t-butyl ether or n-butyl t-butyl ether complexes, such
decomposition would result in the formation of BF.sub.3 methanol (or
butanol) complexes with the release of isobutylene and dimers or trimers
of isobutylene. To prevent such decomposition, gaseous BF.sub.3 can be
bubbled into the ether at a relatively slow rate over a period of about 1
to 5 hours and at a temperature not exceeding about 0.degree. C. A
preferred temperature to minimize breakdown of the etherate complex is
about -60.degree. to about -30.degree. C. If desired, a further means of
controlling the reaction between the BF.sub.3 and the ether is to dilute
the BF.sub.3 with an inert gas such as nitrogen and/or dilute the ether
with inert solvents such as dichloromethane.
Ether having a tertiary carbon bonded to the ether oxygen can be used in
the preparation of the BF.sub.3 -etherates of the present invention.
Suitable ethers include methyl tertiary-butyl ether, ethyl tertiary-butyl
ether, n-propyl tertiary-butyl ether, isopropyl tertiary-butyl ether,
ditertiary-butyl ether, 1,1'-dimethylbutyl methyl ether, and so on. The
tertiary position of the ether is preferably a tertiary butyl group for
smoothest initiation of polymerization and minimization of branching or
skeletal rearrangement in isobutylene polymerization. Also, generally
speaking, as the hydrocarbyl group (preferably alkyl) of the non-tertiary
portion of the ether is increased from methyl to isopropyl to butyl, etc.,
the molecular weight of the resultant polybutene polymer is increased.
The mole ratio of ether to BF.sub.3 in the etherates of the present
invention should be in the range of about 0.5 to about 3:1. Preferably, to
maximize attainment of high vinylidene content in the resulting polybutene
polymer, the ether should be in at least a slight molar excess of the
BF.sub.3, most preferably in the range of about 1:1 to about 1.1:1. At
mole ratios below about 1:1, the vinylidene content begins to decrease.
Above about 1.1:1 little further improvement is observed.
The BF.sub.3 -etherates can be prepared ahead of time for subsequent use as
a preformed catalyst complex, such as when polymerization is to be carried
out in a batch process. In a continuous process the BF.sub.3 -etherates
can be preformed in line immediately prior to entering the polymerization
reaction. If performed ahead of time and stored for subsequent use, the
BF.sub.3 etherates should be maintained at 0.degree. C. or less to prevent
decomposition.
The present invention is also directed to a process for polymerizing a
feedstock comprising 1-olefins which process comprises contacting the
feedstock with the BF.sub.3 -tertiary etherates described above.
The hydrocarbon feedstock may be pure 1-olefin or a mixture of 1-olefins.
1-olefin feedstock where the olefin contains 3 to 16 carbon atoms is
preferred. If a pure olefin is used which is gaseous under ambient
conditions it is necessary either to control the reaction pressure or to
dissolve the olefin in a solvent medium inert under the reaction
conditions in order to maintain the olefin in the liquid phase. In the
case of isobutylene, which is typical of 1-olefins, the feedstock used in
the polymerization process may be pure isobutylene or a mixed C.sub.4
hydrocarbon feedstock such as that resulting from the thermal or catalytic
cracking operation conventionally known as a butadiene or C.sub.4
raffinate. This is a liquid when under pressure and hence no diluent is
needed. The feedstock used may suitably contain between 5 and 100% by
weight of isobutylene. It is preferred to use a feedstock containing at
least about 10% by weight of isobutylene. The hydrocarbon feedstock used
may contain, in addition to isobutylene, butanes and butenes without
adverse effect on the polybutene product.
The polymerization temperature should be selected based on the molecular
weight desired in the product. As is well known, lower temperatures can be
used for higher molecular weights while higher temperatures can be used to
obtain lighter products. The polymerization of the present invention can
be carried out in the full range of temperatures generally associated with
conventional polybutene polymerization, i.e., about -100.degree. C. to
about +50.degree. C. Polybutene molecular weights in the greatest
commercial demand, i.e., those of molecular weight 100 to about 5000 can
be obtained in the polymerization of the present invention at temperatures
in the range of about -50.degree. C. to about +10.degree. C.
The residence time required in the polymerization of the present invention
represents an important advantage over the prior art which generally
teaches short, strictly controlled residence times. For example, in
Boerzel U.S. Pat. No. 4,152,499, it is shown that residence times
exceeding about 10 minutes are detrimental to the vinylidene character of
the polymer. By comparison, typical residence times in the present
invention range from about 10 minutes to 3 hours, while residence times of
greater than 3 hours can be used to produce heavy polymer in reactions
carried out at very low temperatures (i.e., -30.degree. to -100.degree.
C.). Such longer residence times are possible without the adverse effects
upon vinylidene content noted in column 1 of the Boerzel '499 patent.
Generally speaking, while the choice of residence time will be dictated in
a known manner by factors such as the isobutylene concentration in the
feed, temperature of reaction, catalyst concentration and the desired
molecular weight of the product, it should be pointed out that the
residence time should not be allowed to extend longer than the time
required for the isobutylene concentration in the feed to decrease to
about 1 wt % (which can be readily monitored by gas chromatography). If
allowed to continue beyond this point, the polymer is susceptible to
isomerization of the desired vinylidene double bond to the less reactive
trior tetra-substituted internal double bond.
The amount of BF.sub.3 -etherate used in the polymerization is not critical
to the invention. Generally speaking, amounts ranging from at least about
0.01 mole percent based on isobutylene in the feed are suitable. About
0.05 to about 1 mole % is sufficient to obtain conversions of isobutylene
of 80-90%. Generally speaking, raffinate feeds may require higher levels
of the BF.sub.3 complex than would suffice for a feed of pure isobutylene,
to obtain 80-90% conversions. This is believed due to the number of
competing reactions in the raffinate as opposed to synthetic feeds.
The polymerization of the present invention aided by the novel BF.sub.3
-tertiary etherates disclosed herein can be used to obtain a full range of
polybutene molecular weights depending upon conditions of reaction time,
feed, reaction temperature, etc. all of which can be controlled in a known
manner. Polybutene obtained from the present invention having 80 to 100%
vinylidene is more reactive than conventional polybutene having much lower
vinylidene. As such the polybutene prepared in the present invention is
particularly well suited for reaction with maleic anhydride to obtain
valuable PIBSA intermediates useful in the manufacture of fuels and
lubricant additives.
The following examples are intended for illustration only and should not be
construed as limiting the invention set forth in the claims.
EXAMPLE I
Preparation of BF3-Methyl-t-butyl Etherate
Into a 150 ml flask was charged 33 ml (0.28 moles) of methyl-t-butyl ether
(MTBE). The flask of ether was then cooled to -40.degree. C. Gaseous
BF.sub.3 (6610 cc; 0.28 moles) was then slowly bubbled into the ether at a
rate of 22 cc/min. with vigorous stirring. The gas phase of the flask was
continually purged with nitrogen and the vent gases bubbled through 20%
NaOH to remove acidic components. After addition of the BF.sub.3 was
complete, the gas phase of the flask was purged for another 20 minutes to
ensure removal of free BF.sub.3. The BF.sub.3 -methyl t-butyl etherate was
stored at 0.degree. C. until ready for use.
EXAMPLE II
Example I was repeated except that ethyl-t-butyl ether was used instead of
MTBE.
EXAMPLE III
Example I was repeated using n-butyl-t-butyl ether.
EXAMPLE IV
Example I was repeated using isopropyl-t-butyl ether.
EXAMPLE V
Example I was repeated using di-t-butyl ether.
EXAMPLE VI
Example I was repeated using n-propyl-t-butyl ether.
EXAMPLE VII
Example I was repeated using isoamyl-t-butyl ether.
EXAMPLE VIII
Example I was repeated using 1,1'-dimethylbutylmethyl ether.
EXAMPLE IX
Example I was repeated using cyclohexyl-t-butyl ether.
EXAMPLE X
Example I was repeated using benzyl-t-butyl ether.
EXAMPLE XI
The BF.sub.3 -MTBE complex of Example I was used to polymerize a feed
consisting of 20% isobutylene in isobutane. The feed contained less than
1.0 ppm water. Three separate batch polymerizations (summarized in Table 1
below) were run in an autoclave batch reactor equipped with a heat
exchanger and in line cooling coils. The autoclave was cooled to the
desired temperature followed by addition of 550 grams of the feed. The
BF.sub.3 -MTBE complex was charged to a pre-cooled stainless steel bomb
attached to the reactor inlet. The complex was introduced into the reactor
by purging the bomb with 50 grams of the abovementioned feed, followed by
nitrogen to obtain a pressure in the reactor of 200 psi. The reaction
conditions for each run are summarized in the Table 1 below. Each run
produced colorless polybutene having at least 80% vinylidene content.
Product olefin distribution (i.e., relative amount of vinylidene,
tri-substituted and tetra-substituted double bond) was determined by
.sup.13 C NMR.
TABLE 1
______________________________________
Isobutylene Polymerization Using BF3-MTBE
Reaction Mole % of % Isobutylene
Temp (.degree.C.)
Catalyst* Conversion Mn Mw
______________________________________
0 0.05 92 283 441
0 0.10 98 279 409
10 0.29 88 240 303
______________________________________
Dispersion
.sup.13 C NMR Analysis
Index % Vinylidene % Tri % Tetra
______________________________________
1.56 80 17 3
1.59 81 16 3
1.26 81 16 3
______________________________________
*mole % of catalyst relative to isobutylene.
EXAMPLE XII
In a pilot plant continuous reactor cooled to -15.degree. C., BF.sub.3
-MTBE was preformed by in-line mixing of BF.sub.3 and methyl-t-butyl ether
just prior to entering the reactor. The mole ratio of ether to BF.sub.3
was 1:1. The feed was a typical refinery C.sub.4 raffinate (water washed
and dried) containing 18% isobutylene and 5 ppm water. The catalyst load
was 0.36 mole percent in relation to the washed feed. The colorless
product (total polymer) had an olefin distribution of 74% vinylidene, 13%
trisubstituted and 8% tetrasubstituted. The stripped polymer had 87%
vinylidene, M.sub.n =626, M.sub.w =789, dispersion index=1.29 and a flash
point (ASTM D-92 COC) of 242.degree. C.
EXAMPLE XIII
The batch polymerization process outlined in Example XI was repeated except
that BF.sub.3 -butyl-t-butyl etherate (Example II) was used instead of
BF.sub.3 -MTBE. Table 2 below summarizes the reaction conditions and
results for two separate runs. As in Example XI, the feed was 20%
isobutylene in isobutane and virtually anhydrous (<1 ppm H.sub.2 O). Both
runs were conducted at -18.degree. C. with a residence time of 60 minutes.
The mole ratio of ether to BF.sub.3 in the catalyst complex was 1.1:1.
TABLE 2
______________________________________
Isobutylene Polymerization Using BF3-BTBE
Init. Conc.* GPC Data
of BTBE-BF3 Mn Mw DI
______________________________________
0.13 1228 2631 2.14
0.13 1419 2756 1.94
______________________________________
*The concentration of BTBEBF.sub.3 in mole % relative to isobutylene.
Olefin Distribution
13C NMR
% Vinylidene
% Trisubstituted
% Tetrasubstituted
______________________________________
87 8 5
93 7 0
______________________________________
EXAMPLE XIV
The batch polymerization of Example XI was repeated except that BF.sub.3
-butyl-t-ether (BF.sub.3 -BTBE) was substituted for BF.sub.3 -MTBE, and a
water washed (and dried) refinery C.sub.4 raffinate was substituted for
the 20% isobutylene in isobutane feed. Table 4 below summarizes the
results of four separate runs. Each run was carried out at -18.degree. C.
with a residence time of 40 minutes. Raffinate source "A" (Whiting)
consisted of about 14% isobutylene and was dried to <5 ppm H.sub.2 O.
Raffinate source "B" (Texas City) consisted of about 18% isobutylene and
was dried to a moisture content of <5 ppm H.sub.2 O. The mole ratio of
butyl-t-butyl ether to BF.sub.3 in the complex was 1.1:1.
TABLE 3
______________________________________
Isobutylene Polymerization Using
BF3:BTBE and C4 Raffinate
Raffinate Mol % GPC Data
Source Catalyst Mn Mw DI
______________________________________
A 0.76 902 1534 1.70
A 1.01 916 1446 1.77
B 0.52 806 1842 2.29
B 0.78 569 1044 1.83
______________________________________
Olefin Distribution
13C NMR
% Vinylidene
% Trisubstituted
% Tetrasubstituted
______________________________________
84 12 4
80 17 3
81 14 5
80 15 5
______________________________________
EXAMPLE XV
Using the batch polymerization outlined in Example XI, with BF.sub.3 -BTBE
catalyst, the effect on vinylidene content of varying the mole ratio of
BTBE to BF.sub.3 was studied in five separate runs summarized in Table 4
below. The feed was 20% isobutylene in isobutane (<1 ppm H.sub.2 O), the
reaction temperature was -18.degree. C. and the residence time was 40
minutes.
TABLE 4
______________________________________
Effect of Varying Mole Ratio
of Ether to BF3 Upon
Vinylidene Content
Mole Ratio
Mol. % Olefin Dist. .sup.13 C NMR
BTBE/BF3 BTBE:BF3 Vinylidene Tri Tetra
______________________________________
1:1 0.38 76 15 9
1.1:1 0.52 83 17 0
1:1 0.38 75 18 8
0.8:1 0.52 63 30 7
1.1:1 0.62 83 15 2
______________________________________
TABLE XVI
The batch polymerization of Example XI was repeated except that the
BF.sub.3 etherate was prepared from isopropyl-t-butyl ether (PTBE). The
feed was 20% isobutylene in isobutene containing less than 1 ppm H.sub.2
O. Five runs were carried out using a reaction temperature of 0.degree. C.
and a residence time of 50 minutes. The runs are summarized in Table 5
below.
TABLE 5
______________________________________
Isobutylene Polymerization Using BF3:PTBE
Mole Ratio Mol % GPC Analysis
PTBE:BF3 Catalyst Mn Mw DI
______________________________________
1.1:1 0.56 323 478 1.48
1:1 1.56 381 583 1.53
1.1:1 0.42 403 613 1.52
1.1:1 0.56 487 746 1.53
1:1 0.22 713 1272 1.78
______________________________________
Olefin Distribution
13C NMR
% Vinylidene
% Trisubstituted
% Tetrasubstituted
______________________________________
100 1 --
85 13 2
100 -- --
100 -- --
85 11 4
______________________________________
EXAMPLE XVII
For purposes of comparison, BF.sub.3 -ethanol and BF.sub.3 -butanol
complexes were evaluated for their ability to produce polybutene having
high vinylidene content. BF.sub.3 -ethanol and BF.sub.3 -butanol complexes
were prepared using the general procedures of Example I as follows: Into a
flask was charged 1.09 moles of ethanol or butanol. The flask was then
cooled to 0.degree. C. with an ice bath. Gaseous BF.sub.3 (1.09 moles) was
bubbled into the flask with vigorous stirring over a period of about 120
minutes. The gas phase of the reaction vessel was continually purged with
nitrogen and the vent gases bubbled through 20% NaOH to remove acidic
components. Following addition of all the BF.sub.3 the gas phase of the
flask was purged with nitrogen for another 20 minutes to ensure removal of
any free BF.sub.3. The resulting BF.sub.3 ethanol or butanol complexes
were evaluated in a series of runs for polymerization of a feed consisting
of 20% isobutylene in isobutane. In Table 6, below, the concentration of
the BF.sub.3 -alcohol complex was 0.19 mole % based on the feed, the
reaction temperatures were varied (9.degree. C-1.degree. C. and
-10.degree. C.) and the residence times were as long as necessary to react
about 99% of the isobutylene, which in all of the runs was about 20
minutes. The batch polymerizations were carried out according to the
procedures outlined in Example XI. Table 6 below summarizes the results of
3 BF.sub.3 -ethanol runs.
TABLE 6
______________________________________
Isobutylene Polymerization
Using BF3-Ethanol Complex
Reaction GPC Data
Temp. .degree.C. Mw Mn
______________________________________
9 500 300
-1 600 400
-10 1000 600
______________________________________
Olefin Distribution
13C NMR
% Vinylidene
% Trisubstituted
% Tetrasubstituted
______________________________________
76 22 2
73 24 3
80 17 3
______________________________________
A BF.sub.3 -butanol complex as prepared above was evaluated in four batch
polymerization runs using 20% isobutylene in isobutane as the feed. The
catalyst concentration was 0.18 mole %, residence times (allowing for
reaction of 99% of the isobutylene in the feed) were 30 minutes and the
reaction temperatures were -18.degree. C., -12.degree. C., 0.degree. and
10.degree. C. Table 7 below summarizes these four BF.sub.3 -butanol runs.
TABLE 7
______________________________________
Isobutylene Polymerization Using
BF3-Butanol Complex
Reaction GPC Data
Temp. .degree.C. Mw Mn
______________________________________
-18 1700 800
-12 1400 700
0 800 400
.sup. 10.degree.
450 300
______________________________________
Olefin Distribution
13C NMR
% Vinylidene
% Trisubstituted
% Tetrasubstituted
______________________________________
75 18 7
72 21 7
72 22 6
72 23 5
______________________________________
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